Thus, in this work, we used functional genomic techniques to compare in detail the inhibitory actions of Mag 2 and DsS3(1-16). However, membrane disruption alone may not be sufficient to kill microorganisms (reviewed in reference 51). Therefore, it is not surprising that the principal mechanism of cell death induced by these cationic peptides has been attributed to membrane disruption. Similarly, studies on DsS3 have shown that this peptide also binds to, and disrupts, membranes ( 15). Studies of Mag 2 have clearly shown that the peptide binds to negatively charged bacterial membranes and induces the formation of a toroid pore that permeabilizes the membrane ( 29, 51). Magainin 2 (Mag 2) from Xenopus laevis ( 53) and dermaseptin S3(1-16) ( 31), a truncated derivative of DsS3 from Phyllomedusa sauvagii ( 32) with full activity, are unrelated, cationic, α-helical antimicrobial peptides that have been extensively investigated. Evidence from a range of studies has shown that an important target for cationic peptides could be interference with the synthesis or function of critical intracellular macromolecules, such as DNA and proteins. However, increasing evidence indicates that the inhibitory actions of many peptides are complex and involve targets interior to the cytoplasmic membrane ( 51). There is a perception that antimicrobial peptides kill microorganisms nonspecifically by disrupting the plasma membrane of target cells with a detergent-like action. This implies that both peptides are able to pass through the cytoplasmic membrane of yeast cells and damage DNA, an inhibitory action that has not been previously attributed to either of these peptides.Īntimicrobial peptides have now been discovered from the microbial, animal, and plant kingdoms and are classified on the basis of their secondary structures (reviewed in reference 12). Physical techniques revealed that both peptides interacted with DNA in vitro but in subtly different ways, and this observation was supported by the functional genomics experiments that provided evidence that both peptides also interfered with DNA integrity differently in vivo. Thus, DsS3(1-16) and Mag 2 have both common and unique antifungal actions that are not simply due to membrane disruption. Crucially, each peptide also required unique genes for maintaining resistance for example, DsS3(1-16) required genes involved in protein targeting to the vacuole, and Mag 2 required genes involved in DNA-dependent DNA replication and DNA repair. Resistance to both peptides was conferred by genes involved in telomere maintenance, chromosome organization, and double-strand break repair, implicating a common inhibitory action of DNA damage. Gene ontology profiling (of biological processes) was used to identify both common and unique effects of each peptide. Using a combination of global deletion mutant library phenotypic screening, expression profiling, and physical techniques, we have carried out a comprehensive in vitro analysis of the inhibitory action of these two peptides on the model fungus Saccharomyces cerevisiae. Dermaseptin S3(1-16) and magainin 2 (Mag 2) are two unrelated, amphibian-derived cationic peptides that adopt an α-helical structure within microbial membranes and have been proposed to kill target organisms via membrane disruption.
0 Comments
Leave a Reply. |